1. Field of the Invention:
This invention relates generally to insulated screw grommets or snap-in nut devices and more particularly, it relates to an improved enclosed plastic screw grommet of the type adapted to be inserted and retained in an aperture in a panel and thereafter to receive a threaded element, such as a screw, for mounting another apertured member to the panel. In one particular application of the present invention, the screw grommet may be pushed into a bumper of an automobile and a license plate is then positioned over the bumper so that its opening is aligned with the aperture in the screw grommet. Finally, a screw is inserted axially through both the opening in the license plate and the aperture in the screw grommet and is then tightened, thereby securing the license plate to the bumper.
2. Description of the Prior Art:
A state of the art search directed to the subject matter of this application uncovered the following patents:
U.S. Pat. Nos. 2,788,047; 2,984,698; 4,082,030; 4,719,977; and 4,580,859.
British Pat. No. 1,139,976.
However, none of the prior art uncovered in the search disclosed an enclosed plastic screw grommet having a head flange and a shank portion like that of the present invention which reduces the force needed upon insertion into a panel aperture and accommodates a variety of panel thicknesses. This is accomplished by providing four radially extending U-shaped slots formed in the head flange so as to permit flexing upon insertion and by providing two sets of interference ramps which are disposed in an offset relationship with respect to each other on the outer surface of the shank portion.